Dezhi Sun

Facile Fabrication of Bi2

In this report, a novel photocatalyst based on Bi2WO6/Ag2S heterostructures was prepared by a 3-mercaptopropionic acid (MPA)-assisted route at room temperature. Compared to bare Bi2WO6 and Ag2S nanoparticles, the as-formed Bi2WO6/Ag2S heterostructures exhibit enhanced photocatalytic activity for the degradation of rhodamine B (Rh B) under visible-light irradiation. This kind of enhancement in the photocatalytic activity is considered to be the synergistic effects of both the effective electron-hole separation and expansion of the light-absorption range. The pH of the solution is of vital importance to the photocatalytic activity of the as-formed Bi2WO6/Ag2S heterostructures. Under low pH value, the photosensitization process is suppressed, while under higher pH value, the photosensitization process is favored. The mechanism of the photocatalytic process was proposed by the active-species-trapping experiments, indicating that the photogenerated holes (h+) play a crucial role in the degradation of Rh B under visible light. The enhanced photocatalytic performance of this heterostructure makes it a promising material for the treatment of dye-containing wastewater.

Crystalline structures and mesomorphic properties of gemini diammonium surfactants with a pendant hydroxyl group.

A series of homologous crystals of gemini diammonium surfactants (GDAS) containing one hydroxyl substituted methylene spacer are prepared. The crystal structures of these compounds, namely [C(n)H(2)(n)(+1)-N(+) (CH(3))(2)-CH(2)CH(OH)CH(2)-N(+)(CH(3))(2)-C(n)H(2)(n)(+1)], are determined by single-crystal X-ray diffraction techniques, in order to have a better understanding of the structure relation between the solid and the mesophase. The hydroxyl groups enhance the hydrogen bonding interaction between neighboring compounds, and therefore the packing of GDAS in the solid state is arranged to form a herringbone-like mode. To the best of our knowledge, this is the first GDAS crystal with a herringbone-like structure. Their mesomorphic properties are investigated by differential scanning calorimetry, polarizing optical microscopy, X-ray powder diffraction, and rheological measurement. These compounds have relatively low melting points and form thermotropic mesophases over a broad temperature range, as compared to those without a hydroxyl substituted at the spacer. The rheological behavior of the smectic phases clearly reveals that hydrogen bonds exert a significant effect on the high values of moduli and viscosity. Moreover, the melting point and rheological parameters increase, conforming to the length of alkyl chains.

A Chain-Based 2 D Cobalt(II) Coordination Polymer with a “Crab-Like” Flexible Dicarboxylate Ligand: A Weak Ferromagnetic Single-Chain Magnet

Chain gang: A chain-based 2D Co(II) coordination polymer was prepared by hydrothermal reaction of Co(NO3)2⋅6 H2O, H2L and bpa in the presence of sodium hydroxide. Magnetic investigation revealed canted antiferromagnetism, magnetic hysteresis, and slow magnetic relaxation. Thus, this complex could be considered as a new homospin weak ferromagnetic single-chain magnet.

Enhanced photocatalytic performance in Bi2WO6/SnS heterostructures: Facile synthesis, influencing factors and mechanism of the photocatalytic process.

Highly-efficient photocatalyst based on Bi2WO6/SnS heterostructure was prepared via a surface functionalization method using 3-mercaptopropionic (MPA) as the surface functionalizing agent. Compared to bare Bi2WO6 and SnS nanoparticles, the as-formed Bi2WO6/SnS heterostructure exhibits enhanced photocatalytic activity for the degradation of Rhodamine B (Rh B). Photoluminescence and photocurrent measurements demonstrate that the enhanced photocatalytic activity during the photocatalytic process is closely related to the enhanced electron-hole separation efficiency. The photocatalytic activity of the as-formed Bi2WO6/SnS heterostructure can be perfectly remained even after being used for five times, showing excellent durability during the photocatalytic process. The influence of pH and inorganic ions are systematically investigated. And the optimum pH for the photocatalytic process is determined to be 6. The addition of chloride ion will exert negative effect on the photodegradation process of Rh B. The mechanism of photodegradation process was investigated by exploring the quenching effects of different scavengers and the results suggest that the reactive holes play the major role in the photodegradation process of Rh B.

Formation and properties of wormlike micelles in solutions of a cationic surfactant with a 2-hydroxypropoxy insertion group

The rheological properties of aqueous solutions of a cationic surfactant, 3-hexadecyloxy-2-hydroxypropyl trimethyl ammonium bromide (R16HTAB), and its mixed solution system with sodium salicylate (NaSal) have been studied by using steady state and frequency sweep rheological measurements. The microstructure of the formed wormlike micelles has been ascertained by transmission electronic microscopy and 1H NMR technology. The effects of the surfactant concentration, added salt, temperature and different counterions on the viscoelastic solutions have been systematically investigated. In a salt-free state, the η0 and R16HTAB concentrations obey the relationship of the power law, i.e. η0 ∝ C2.53, in the examined concentration range. The addition of NaSal greatly promoted the micellar growth in R16HTAB aqueous solution and resulted in the generation of wormlike micelles. The causes of the formation of wormlike micelles and the strong network structure have been analyzed.

Facile Fabrication of Bi2WO6/Ag2S Heterostructure with Enhanced Visible-Light-Driven Photocatalytic Performances

In this report, a novel photocatalyst based on Bi2WO6/Ag2S heterostructures was prepared by a 3-mercaptopropionic acid (MPA)-assisted route at room temperature. Compared to bare Bi2WO6 and Ag2S nanoparticles, the as-formed Bi2WO6/Ag2S heterostructures exhibit enhanced photocatalytic activity for the degradation of rhodamine B (Rh B) under visible-light irradiation. This kind of enhancement in the photocatalytic activity is considered to be the synergistic effects of both the effective electron-hole separation and expansion of the light-absorption range. The pH of the solution is of vital importance to the photocatalytic activity of the as-formed Bi2WO6/Ag2S heterostructures. Under low pH value, the photosensitization process is suppressed, while under higher pH value, the photosensitization process is favored. The mechanism of the photocatalytic process was proposed by the active-species-trapping experiments, indicating that the photogenerated holes (h+) play a crucial role in the degradation of Rh B under visible light. The enhanced photocatalytic performance of this heterostructure makes it a promising material for the treatment of dye-containing wastewater.

Inclusion complexes of quercetin with three β-cyclodextrins derivatives at physiological pH: Spectroscopic study and antioxidant activity

Properties of the inclusion complexes of quercetin (QUE) with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD) in tris-HCl buffer solutions of pH 7.40 were investigated. The stoichiometry and thermodynamic parameters for the complexation process (stability constants K, Gibbs free energy change ΔG, enthalpy change ΔH and entropy change ΔS) were determined using phase-solubility and fluorescence spectra analysis. The thermodynamic studies indicated that the inclusion reactions between QUE and the three β-CDs are enthalpy-driven processes. Proton nuclear magnetic resonance spectroscopy indicated that B-ring, C-ring, and part of A-ring of QUE interact with the cavity of β-CDs. The antioxidant activity of QUE and its inclusion complexes were determined by the scavenging of stable radical DPPH(*). The results showed that the complexed QUE/CDs were more effective than free QUE, with the QUE/SBE-β-CD complex as the best form.

Phase behavior of new aqueous two-phase systems: 1-Butyl-3-methylimidazolium tetrafluoroborate + anionic surfactants + water

The aqueous mixtures of an anionic surfactant (sodium dodecyl benzene sulfonate, SDBS) and an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim]BF4) within a certain range of compositions can spontaneously separate into two immiscible aqueous phases (ATPS): one surfactant-rich and the other ionic liquid-rich. The phase diagrams of the ternary system of the SDBS/[Bmim]BF4/water were drawn based on experimental data determined at 10.0, 20.0 and 30.0 °C, respectively. The borderlines of the different specific regions in the diagrams were determined using turbidity titration method. The narrow two-phase region aqueous were found to be close to the water - [Bmim]BF4 side. The formation conditions, compositions, and physicochemical properties of the aqueous two phases have been studied. The effects of temperature, surfactant and ionic liquid content on the phase separation time and phase volume ratio of the ATPS were also investigated. This phase separation phenomenon was found to be likely due to the existence of micelle aggregates with quite large size obtained by Transmission Electron Microscopy (TEM) and Steady-state Fluorescence Quenching Measurements (SFQM) methods.

Microcalorimetric and spectrographic studies on the interaction of DNA with betaxolol

The interaction of calf thymus deoxyribonucleic acid (ct-DNA) with betaxolol (BET) in aqueous buffer solution (pH 7.40) has been investigated using isothermal titration calorimetry (ITC), ultraviolet absorption (UV), fluorescence spectroscopy (FS) and circular dichroism (CD). Thermodynamic parameters, i.e., equilibrium constants, standard changes of enthalpy (DeltaH degrees ), Gibbs free energy (DeltaG degrees) and entropy (DeltaS degrees ), for the binding process of the drug to the bio-macromolecules have been derived from the calorimetric data. Analysis of the thermodynamic data indicates that there are two classes of binding sites on the DNA molecules being able to coordinate with BET molecules. One class of binding takes place at the sites formed by base pairs, which is synergistically driven by enthalpy and entropy, while the other one takes place on phosphate groups and shown as an entropy driven process. The thermodynamic behavior of the DNA-drug supramolecular system has been discussed in the light of the important weak interactions, hydrophobic force, hydrogen bond and electrostatic force, according to the UV, FS and CD spectra.

Novel Bake-in-Salt Method for the Synthesis of Mesoporous Mn3O4@C Networks with Superior Cycling Stability and Rate Performance

The commercial applications of Mn3O4 in lithium ion batteries (LIBs) are greatly restricted because of the low electrical conductivity and poor cycling stability at high current density. To overcome these drawbacks, mesoporous Mn3O4@C networks were designed and synthesized via an improved bake-in-salt method using NaCl as the assistant salt, and without the protection of inert gas. The added NaCl plays a versatile role during the synthetic process, including the heat conducting medium, removable hard template and protective layer. Because of the homogeneous distribution of Mn3O4 nanoparticles within the carbon matrix, the as-prepared Mn3O4@C networks show excellent cycling stability in LIBs. After cycling for 950 times at a current density of 1 A g-1, the discharge capacity of the as-prepared Mn3O4@C networks is determined to be 754.4 mA h g-1, showing superior cycling stability as compared to its counterparts. The valuable and promising method, simple synthetic procedure and excellent cycling stability of the as-prepared Mn3O4@C networks makes it a promising candidate as the potential anode material for LIBs.